SEC Petition Evaluation Report 

Petition SEC-00079 

Report Rev #: Addendum 2 Report Submittal Date: June 3, 2008

Subject Expert(s): James Mahathy 

Site Expert(s): N/A 

Petitioner Administrative Summary 

Petition Under Evaluation 

Petition # Petition 

Type 

Petition A 

Receipt Date DOE/AWE Facility Name 

SEC-00079 83.14 November 28, 2006 Dow Chemical Company (Madison Site) 

Proposed Class Definition 

All Atomic Weapons Employer employees who were monitored, or should have been monitored, for 

exposure to thorium radionuclides while working at the Dow Chemical Company site in Madison, 

Illinois, for a number of work days aggregating at least 250 work days from January 1, 1957 through 

December 31, 1960, or in combination with work days within the parameters established for one or 

more other classes of employees in the Special Exposure Cohort.

Related Petition Summary Information 

SEC Petition Tracking #(s) Petition Type DOE/AWE Facility Name Petition Status 

NONE 

Related Evaluation Report Information 

Report Title DOE/AWE Facility Name 

SEC Petition Evaluation Report, SEC-00079 Dow (Madison Site) 

SEC Petition Evaluation Report, SEC-00079, 

Addendum 1 

Dow (Madison Site) 

Peer Review Completed By: [Signature on file] 06/03/2008 

 L. Rutherford Date 

SEC Petition Evaluation Reviewed By: [Signature on file] 06/03/2008 

 J. W. Neton Date 

SEC Evaluation Approved By: [Signature on file] 06/03/2008 

 Larry Elliott Date 
SEC-00079 Addendum 2 06-03-08 Dow Madison

2 of 34 

This page intentionally left blank 
SEC-00079 Addendum 2 06-03-08 Dow Madison

3 of 34 

 Addendum 2 to Dow Madison (SEC-00079) 

Special Exposure Cohort Evaluation Report 

NOTE: This Addendum only addresses those sections in the Dow Madison Evaluation Report that 

require discussion. Therefore, the section numbering is not contiguous. 

ATTRIBUTION AND ANNOTATION: This is a single-author document. All conclusions drawn from 

the data presented in this evaluation were made by the ORAU Team Lead Technical Evaluator: James 

Mahathy; Oak Ridge Associated Universities. These conclusions were peer-reviewed by the 

individuals listed on the cover page. The rationales for all conclusions in this document are explained 

in the associated text. 

NIOSH presented a Special Exposure Cohort (SEC) evaluation report (NIOSH, 2007) about the Dow 

Chemical Company, Madison, Illinois (Dow Madison) to the Presidential Advisory Board on 

Radiation and Worker Health during the Advisory Board’s regular meeting on May 3, 2007. The 

report evaluated the feasibilities of reconstructing radiation doses arising from the use of uranium and 

thorium during the Atomic Weapons Employer (AWE) operations period from January 1, 1957 

through December 31, 1960 and from exposure to residual uranium from January 1, 1961 through 

December 31, 1998. The feasibility of reconstructing doses received from exposure to residual 

thorium was not considered because the Department of Energy (DOE) characterized thorium use 

during the AWE operations period as commercial. Commercial sources of radiation exposure at AWE 

sites must be considered in the assessment of dose received during AWE operational periods. 

However, non-AEC thorium doses received during the site’s residual radiation period are not included 

in the assessment of site doses. NIOSH stated in the evaluation report that doses received from 

exposures to uranium could be reconstructed during both the operations and residual periods, but 

exposure to thorium, although used commercially, could not be accurately reconstructed during the 

AWE operations period and recommended adding a class on this basis. On May 23, 2007, the 

Advisory Board recommended to the Secretary, Department of Health and Human Services that Dow 

Madison be added as a class to the SEC. On June 22, 2007, the Secretary sent letters to the House and 

Senate specifying that Dow Madison be added to the SEC. 

In January, 2008, the DOE notified the Department of Labor (DOL) and NIOSH that after additional 

research, DOE had concluded that Dow Madison did use thorium in AWE operations. DOE stated 

that in 1957 and 1958 Dow Madison supplied the Atomic Energy Commission (AEC) (via the 

Mallinckrodt site) with Mg-Th plates and sheets, and that during this time period, these types of plates 

and sheets were used in atomic weapons (DOE, 2008). The DOE concluded that, for the years 

1957-58: (1) Dow Madison probably produced material for use by the AEC; (2) the material emitted 

radiation; (3) the material could have been used in the production of an atomic weapon; and (4) Dow 

Madison’s work with Mg-Th plates and sheets is, therefore, a covered AWE operation (DOE, 2008). 

Since the topic was not addressed in the first Evaluation Report, NIOSH evaluated the feasibility of 

reconstructing doses from potential exposures to residual thorium contamination. The NIOSH 

evaluation is presented in this addendum. 
SEC-00079 Addendum 2 06-03-08 Dow Madison

4 of 34 

Petition Evaluation Report Summary 

NIOSH-Proposed Class Definition

NIOSH finds that potential radiation doses received from exposure to residual thorium at Dow 

Madison from January 1, 1961 through October 31, 2006 can be reconstructed with sufficient 

accuracy. No changes to the SEC class definition are recommended by NIOSH. This addendum will 

be provided to the DOL to assist it in implementing the current class definition. 

 Feasibility of Dose Reconstruction

NIOSH possesses sufficient information, which includes sufficient personnel and workplace 

monitoring data and radiological source term information to allow NIOSH to estimate the potential 

total internal and external exposures during the residual radiation period at Dow Madison 

4.1 Operations Description 

Uranium operations are not applicable to this addendum and are not discussed herein. Before 

evaluating exposure to residual thorium, Dow Madison thorium operations conducted during the 

AWE period will be briefly reviewed. 

Dow Madison manufactured magnesium alloys that also contained thorium. Dow Madison used one 

large building complex with separate building numbers assigned to portions of the building (i.e., all 

buildings were under the same roof structure). The alloying processes used for manufacturing the 

Mg-Th alloys were documented (AEC, 1960a; Lowery, 1962, Nussbaumer, 1962). Thorium was 

added to the magnesium melt in the Melt Room at the rate of a 3% to 4% mixture and then the Mg-Th 

alloy was poured in the Pump-Off area (next to the Melt Room). The production area in the Melt 

Room building consisted of a work bench, an instrument panel, six crucibles, and one mold. The 

ceiling in the production area was 65-feet high. The room contained three 20-foot exhaust fans. 

Ancillary mechanical and finishing operations were conducted in buildings adjacent to the Melt Room 

building. These operations included the grinding, filing, buffing, and milling of alloy, and the 

collection and drumming of dusts that resulted from the other operations. 

Slag and sludge remaining in the crucible was re-melted and the process was repeated. Sludge 

remaining after the second melting contained up to 50% thorium. The sludge was broken into pieces 

and re-melted. After a third pouring, the remaining sludge, containing up to 8 % thorium was 

transported to the waste yard, later known as the 40-acre CONALCO site. Dow Chemical made some 

attempts to recover thorium stored in the waste yard by grinding the sludge. According to an AEC 

compliance inspection report, Dow segregated the sludge for possible future thorium recovery (AEC, 

1960b); however, NIOSH has no documentation confirming that recovery occurred. An AEC 

inspection report states that alloy scrap was also stored (but segregated) at various points throughout 

the Melt Room building (AEC, 1960a). This statement is consistent with statements in the claimantsupplied affidavits (Kusmierczak, 2007). 
SEC-00079 Addendum 2 06-03-08 Dow Madison

5 of 34 

Mg-Th scrap was recycled at least once through the melting/alloying process. There would have been 

little potential for surface or airborne contamination from the stored scrap, although there was 

potential for some oxidation on the material surface and subsequent entrainment of the oxide. 

Remaining waste was buried in the waste yard. 

AEC license documentation (AEC, 1963; AEC, 1965) limited the authorized quantity of thorium at 

any one time to no more than 111,000 pounds; however, this amount was the maximum allowed for 

Midland, Bay City and Madison in total. Mg-Th production runs used from 4,000 to 30,000 lbs. of 

alloy (AEC, 1960a) with the highest thorium concentration being 4% (equivalent to 1,200 lbs. for a 

30,000 lb. run). This information on quantities is useful in determining waste source terms arising 

from the commercial operations from 1961 onward. According to Dow source material licensing 

documents, film badges were to be used for some workers and those services were contracted to 

Health Physics Services; however, NIOSH has not located that data. 

Dow continued to make Mg alloys for commercial purposes (including some with thorium) from 1961 

through 1969. Dow Chemical sold the Dow Madison plant and the right-to-use patent to Consolidated 

Aluminum (CONALCO) in 1969. CONALCO received by-product license STB-1097 for thorium. 

As late as 1972, Dow continued to send between 300 and 500 pounds per month of thoriumcontaining alloy waste from their Bay City and Midland operations to Madison for disposal (Dow, 

1972). 

In the late 1970s, thorium-bearing slag arising from commercial operations was buried at the waste 

yard (Baker, 1992). By the early 1980s, CONALCO stopped putting waste materials in the yard 

(Mura, 1986). CONALCO produced commercial thorium alloy and shipped thorium wastes off-site to 

a commercial radioactive disposal site in Barnwell, South Carolina. However, thorium wastes were 

stored in an on-site area other than the 40-acre CONALCO yard. 

In 1982, CONALCO had a radiation safety plan as part of a source material licensing package. 

According to source material licensing documents, film badges were to be used for some workers and 

those services were contracted to R. S. Landauer. CONALCO sold the plant to Spectrulite 

Consortium in 1986. CONALCO assumed responsibility for the 40-acre thorium waste yard, but 

Spectrulite assumed responsibility for thorium production (Mura, 1986). Spectrulite Consortium filed 

for bankruptcy in 2003; Magnesium-Elektron bought the remaining inventory and assets but 

production operations were discontinued. Because the work discussed above was commercial, it is 

not considered in this evaluation. 

NIOSH reviewed documented waste and clean-up operations conducted during the residual period to 

assess the potential for thorium exposures. CONALCO produced commercial thorium alloy and 

shipped thorium wastes off-site to a commercial radioactive disposal site in Barnwell, South Carolina. 

However, some amount of thorium scum that formed on molten metals was stored in an on-site area 

other than the 40-acre CONALCO yard. 

Staff at the Oak Ridge National Laboratory (ORNL) performed a radiological survey at the Dow 

Madison site in March 1989 (ORNL, 1990). Among the data published in the report are surface 

smears and dust sample results for samples taken in Building 6 where thorium processing was 

performed. Smear results revealed concentrations above the DOE regulatory limit for Th-232 (1000 

dpm/100 cm2

) in dust sampled from overhead beams at the south end of Building 6 (ORNL, 1990). 
SEC-00079 Addendum 2 06-03-08 Dow Madison

6 of 34 

The maximum surface contamination of thorium in dust was measured at 1,730 dpm/cm2

 (7.8 pCi/g 

Th-232), or 1.7 times the average surface contamination guideline limit of 1000 dpm. 

In 1992, the Madison Site was added to the FUSRAP list of sites slated for clean-up. The FUSRAP 

site was within a limited area of an active facility. The plant was in heavy production, extruding 

aluminum and magnesium metal. Because clean-up was ultimately necessary, the operator worked 

with the U.S. Army Corps of Engineers (USACE) to identify an available timeframe for clean-up. It 

was the intent of the facility owner and the USACE that production operations were not to be 

disrupted during clean-up and that safety of maintenance and production personnel continued to be 

protected (USACE, 1999). 

In 1992, 90,000 cubic yards of soil were removed by firms under contract to CONALCO and Dow 

Chemical which had retained some of the responsibility for clean-up of the slag. Approximately 

1,000 railcars of radioactive waste were sent to commercial disposal sites. CONALCO's radioactive 

materials license for the 40-acre waste yard was terminated in January 1993. Environmental 

Restoration Group (Colorado) provided environmental and health physics support during the 

1992-1993 clean-up (Baker, 1992). CONALCO reported that the 40-acre waste yard contained 

3.3E+6 pounds of total alloy waste containing 1.3E+5 pounds of thorium (NRC, 1986). 

Soil containing Th-232 was removed by Spectrulite during the period January - July 1998 (Huber, 

1998). Wastes removed in 1998 originated from CONALCO commercial operations. In 1999, the 

U.S. Army Corps of Engineers (USACE) developed a characterization report for the Madison Site 

(USACE, 1999, USACE, 2000). Samples were taken to validate existing site data, define site 

contamination, and update the estimate of associated risk. The Characterization Report confirmed the 

presence of contamination in the dust on overhead hard-to-reach surfaces; no contamination measured 

on floors and equipment exceeded release criteria (USACE, 2001). The final clean-up remedy was 

outlined in the final Record of Decision released in early June 1999. In late June 1999, the USACE 

deployed its contractor to the Madison site for decontamination of Building 6. By mid-July, 

independent surveys confirmed that the USACE had successfully decontaminated the site (USACE, 

2001). Forty cubic yards of contaminated dust and materials were sent to a licensed, out-of-state 

facility for disposal. Having completed site remediation, the USACE initiated site closeout to 

successfully remove the site from the list of active FUSRAP sites. However, additional surveys 

conducted by Pangea Group in 2002 in Buildings 4, 5, 6, 7, and 8 revealed levels of Th-232 sufficient 

to warrant clean-up (Pangea, 2005). Some thorium contamination was not removed until October, 

2006 (by Pangea Group) (Cushman, 2008). Potential exposures resulting from clean-up operations 

were considered as part of this addendum, but consideration was only given to the amount of waste 

materials resulting from AWE operations. 

4.3 Time Period Associated with Radiological Operations 

DOE had defined the residual period to be from January 1, 1961 through December 31, 1998. 

However, NIOSH has obtained documentation that demonstrates that contamination attributable to 

AEC-covered uranium and thorium operations was removed in 2006 (Cushman, 2008). Therefore, 

NIOSH has initiated a revision to the Report on Residual Radioactive and Beryllium Contamination at 

Atomic Weapons Employer Facilities and Beryllium Vendor Facilities (NIOSH, 2006) to extend the 

covered residual period through October 31, 2006. 
SEC-00079 Addendum 2 06-03-08 Dow Madison

7 of 34 

4.4 Site Locations Associated with Radiological Operations 

NIOSH has found information to suggest that thorium operations were not limited to a single building. 

Further, NIOSH has documented that slag and sludge were buried in the waste yard. Therefore, 

NIOSH has concluded that exposure to residual thorium was possible in all areas of the Dow Madison 

site. 

4.5 Job Descriptions Affected by Radiological Operations 

NIOSH has not obtained any additional documentation that can be used to restrict the class description 

to specific workers, or documentation that can be used to assign workers to particular job categories. 

Therefore, it is still not possible to use job descriptions to define the class. 

5.0 Summary of Available Monitoring Data for the Proposed Class 

NIOSH has not obtained additional personal or area monitoring data for the AWE operations period 

since the first ER Addendum was published in August, 2007. However, NIOSH has identified 

documents detailing material licenses and information on clean-up activities conducted at the Dow 

Madison Site (Baker, 1992; Huber, 1998; USACE, 1999; USACE, 2000; USACE, 2001; Pangea, 

2005; Cushman, 2008). 

NIOSH document capture activities are listed in Attachment 1. 

5.1 Internal Personnel Monitoring Data 

NIOSH does not have access to any documents that contain personnel bioassay monitoring data for 

Dow Madison site employees. 

5.2 External Personnel Monitoring Data 

NIOSH has obtained film badge results for workers at the Dow Chemical Bay City site who were 

involved in similar operations. However, no film badge results have been obtained by NIOSH for 

Dow Madison workers, neither during the AWE operations period nor the residual radiation period. 

 

5.3 Workplace Monitoring Data 

NIOSH has not identified any area air sampling data obtained during the residual radiation period at 

Dow Madison except for results obtained during a final clean-up of the site conducted in 2006 

(Cushman, 2008). NIOSH also has access to breathing zone and general area air samples collected 

from 1957 through 1959 (Hoyle, 1957; Dow, 1959; Shrader, 1959) though some of these were 

obtained at Madison and some at Midland. NIOSH has access to results of thoron monitoring 

(Shrader, 1959) conducted at Dow Madison in 1959 during operations that used HK-31, (the alloy 

containing the highest percentage of thorium). 

NIOSH has obtained dose rate data obtained by Dow Chemical in the AWE operations period 

(Silverstein, 1957; Levy, 1957) and from monitoring conducted during the residual radiation period in 

1981 (Stein, 1982). 
SEC-00079 Addendum 2 06-03-08 Dow Madison

8 of 34 

5.4 Radiological Source Term Data 

In the Dow Madison Evaluation Report, NIOSH determined that the source term for the AWE period 

included Th-232 with in-growth of thorium daughters.

6.1 Feasibility of Estimating Internal Exposures 

Internal exposures to thorium during the residual radiation period would have resulted from potential 

corrosion of stored material, re-suspension of dust, scrap handling, scrap cutting, and potential loss of 

containment of disposed materials. In order to reconstruct internal doses with sufficient accuracy, 

NIOSH must have access to worker bioassay data, breathing zone and/or area air monitoring data or 

have accurate information that can be used to define the source term and its activity. No personnel 

bioassay monitoring results for thorium have been located by NIOSH. Workplace thorium air 

monitoring results are available for the AWE period and for 2006. 

NIOSH has determined that there is sufficient documentation on the processes and controls used at 

Dow Madison to create a bounding estimate of the concentration of thorium in air on January 1, 1961, 

the start of the residual radiation period. NIOSH considered the potential exposure arising from 

residual operations within buildings, residual operations in the waste yard, and release of thorium 

buried in the waste yard. However, workers would not have been exposed to building and waste yard 

intakes at the same time. 

Potential annual inhalation intakes of thorium and thorium daughters for the January 1, 1961 through 

October 31, 2006 residual period can be bounded using air monitoring data obtained from 1957 

through 1960 and data obtained at Dow Madison in 2006. In order to derive the intake associated 

with residual activities conducted within buildings, NIOSH used general air sampling results obtained 

during the AWE operations period from 1957 through 1959 (Hoyle, 1957; Dow, 1959; Shrader, 

1959). Process and breathing zone samples were excluded, the rationale being that general area air 

samples collected during operations would represent contributions from both re-suspension of surface 

contamination and dispersion of process releases and, as such, would bound the contribution from resuspension of surface activity alone. Ingestion intakes can be bounded using Estimation of Ingestion 

Intakes (NIOSH, 2004). Bounding analyses for thorium are presented in Attachment 2. 

The intake of thoron on January 1, 1961 can also be bounded using thoron monitoring results obtained 

in 1959 (Shrader, 1959); this analysis is also presented in Attachment 2. 

Internal doses received from potential exposures to thorium and thoron can be bounded based on the 

available information on the Dow Madison alloy process, and available workplace monitoring results. 

The methodology to reconstruct internal doses is presented in Attachment 2. 

6.2 Feasibility of Estimating External Exposures 

External doses received from potential exposures to thorium can be bounded; the analysis of available 

data and bounding methodology are presented in Attachment 2. 
SEC-00079 Addendum 2 06-03-08 Dow Madison

9 of 34 

7.0 Summary of Feasibility Findings for Petition SEC-00079 

This addendum to the Dow Madison Evaluation Report evaluates the feasibility for estimating the 

dose, with sufficient accuracy, for all AWE employees who worked at the Dow Chemical Company 

site in Madison, Illinois during the residual period from January 1, 1961 through October 31, 2006. 

NIOSH determined that it has sufficient source term information, workplace monitoring data for 

thorium radionuclides, and process descriptions to allow adequate bounding of the total potential 

AEC-related internal and external exposures at the facility during this time period. Consequently, 

NIOSH finds that it is feasible to estimate with sufficient accuracy the radiation doses resulting from 

internal and external thorium exposures received by members of this class of employees. 

With the data currently available to NIOSH, it is feasible to reconstruct with sufficient accuracy the 

external and internal doses resulting from exposure to uranium metal during the Dow Madison AWE 

operational period (January 1, 1957 through December 31, 1960). NIOSH also considers adequate 

reconstruction of medical dose for Dow Madison workers to be feasible for the AWE operational 

period. 

NIOSH has documented herein that it can complete the dose reconstructions related to this addendum, 

(i.e., doses that resulted from exposure to residual thorium from January 1, 1961 through October 31, 

2006). The basis of this finding is specified in this report, which demonstrates that NIOSH does have 

access to sufficient information to estimate with sufficient accuracy either the maximum radiation 

dose incurred by any member of the class or to estimate such radiation doses more precisely than a 

maximum dose estimate. Members of this class at the Dow Chemical Company site in Madison, 

Illinois, may have received unmonitored internal and external radiological exposures from 

AEC-related thorium radionuclides. NIOSH possesses sufficient information, which includes 

sufficient personnel and workplace monitoring data and radiological source term information to allow 

NIOSH to estimate the potential total internal and external exposures to which the proposed class may 

have been exposed. 
SEC-00079 Addendum 2 06-03-08 Dow Madison

10 of 34 

This page intentionally left blank 
SEC-00079 Addendum 2 06-03-08 Dow Madison

11 of 34 

10.0 References 

AEC, 1960a, Compliance Inspection Report: Dow Chemical Co. Site, Madison, Illinois; U. S. Atomic 

Energy Commission; August 4, 1960; SRDB Ref ID: 29268 

AEC, 1960b, Compliance Inspection Report: Dow Chemical Co. Site, Madison, Illinois; U. S. Atomic 

Energy Commission; November 30, 1960; SRDB Ref ID: 29604 

AEC, 1963, Memo from Donald Nussbaumer to W. Otis Heath, Atomic Energy Agency, May 6, 

1963; SRDB Ref ID: 29636 

AEC, 1965, AEC Material License for the Dow Chemical Company, Midland, Michigan, Atomic 

Energy Agency, March, 1965; SRDB Ref ID: 29673 

Baker, 1992, Madison Site Cleanup, Final Report, prepared by Ken Baker, Environmental Restoration 

Group, December, 1992; SRDB Ref ID: 43582. 

Cushman, 2008, Email concerning Madison Site, Matt Cushman, Pangea Group, March 5, 2008; 

SRDB Ref ID: 41940. 

DOE, 2008, Letter from Department of Energy to Department of Labor, January 8, 2008; SECIS 

SRDB Document ID: 105199 

Dow, 1959, Annual Industrial Hygiene Summary May 1959, D. J. Levy and H. R. Hoyle; Dow 

Chemical Corporation, July 27, 1959; SRDB Ref ID 39912 

Dow, 1972, Partial letter from Dow Chemical Company to Robert Layfield (AEC), Dow Chemical 

Company, Midland, Michigan, July 28, 1972; SRDB Ref ID: 29702 

Baker, 1992, Madison Site Cleanup Final Report, K. R. Baker for Environmental Restoration Group, 

Albuquerque, New Mexico for the State of Illinois, Department of Nuclear Safety; December 1992; 

SRDB Ref ID: 43582 

Hoyle, 1957, Thorium Handling, Alpha Counters and Sludge Recovery Hazards, H. R. Hoyle; Dow 

Chemical Corporation; December 20, 1957; SRDB Ref ID 39998 

Huber, 1998, Uniform low-level radioactive waste manifests and other documents, Stan A. Huber and 

Associates, 1998; SRDB Ref ID: 41934 

Kusmierczak, 2007, Affidavits of former Dow Madison workers regarding thorium, J. Joseph 

Kusmierczak, Simmons Cooper, LLC, April 16, 2007; SRDB Ref ID: 39868 

Levy, 1957, Memo from D. J. Levy, Dow Chemical Company, Madison, IL, March 8, 1957; SRDB 

Ref ID: 39977 
SEC-00079 Addendum 2 06-03-08 Dow Madison

12 of 34 

Lowery 1962, Radiation Hazards in Arc Melting Thorium, Report of Investigations 5969, R. R. 

Lowery, Department of the Interior, 1962; SRDB Ref ID: 40074 

Mura, 1986, Memo and attachments from William Mura (CONALCO) to Bruce Mallet (NRC), 

Consolidated Aluminum Company, August 21, 1986; SRDB Ref ID: 29727, pdf pp. 4-5 

NIOSH, 2004, Estimation of Ingestion Intakes, Rev. 0, Office of Compensation Analysis and Support 

(OCAS); OCAS-TIB-009, National Institute for Occupational Safety and Health (NIOSH); April 13, 

2004. 

NIOSH, 2006, Report on Residual Radioactive and Beryllium Contamination at Atomic Weapons 

Employer Facilities and Beryllium Vendor Facilities, National Institute for Occupational Safety and 

Health, December 2006; http://www.cdc.gov/niosh/ocas/ocasawe.html#residcont

NIOSH, 2007, SEC Petition Evaluation Report Petition SEC-00079, National Institute for 

Occupational Safety and Health, November 28, 2006; SRDB Ref ID: 39873. 

NRC, 1986, Memo from George McCann to William Mura (Dow), Nuclear Regulatory Commission, 

October 3, 1986; SRDB Ref ID: 29727, pdf pp. 2-3 

NUREG 1400, Air Sampling in the Workplace, U.S. Nuclear Regulatory Commission; September 

1993; http://www.hss.doe.gov/HealthSafety/WSHP/radiation/NUREG-1400.pdf 

Nussbaumer, 1962, Memo from Donald Nussbaumer, Dow Chemical Company, January 15, 1962; 

SRDB Ref ID: 40439. 

ORNL, 1990, Preliminary Results of the Radiological Survey at the Former Dow Chemical Company 

Site, Madison, Illinois; ORNL/TM-11552, W. D. Cottrell and J. K. Williams; December, 1990; SRDB 

Ref ID: 3947 

Pangea, 2005, Final Radiological Characterization Report on the Spectrulite Consortium Madison, IL 

Facility, Pangea Group, March, 2005; SRDB Ref ID: 42408. 

Shrader, 1959, Air Sample Data and Calculations, S. A. Shrader; Dow Chemical Corporation; 

December 16, 1959; SRDB Ref ID 39914 

Silverstein, 1957, Industrial Hygiene Experience with Magnesium-Thorium Alloys, Lawrence G. 

Silverstein, Dow Chemical Corporation, June 19, 1957; SRDB Ref ID: 29269. 

Stein, 1982, Radiological Survey Conducted During the 8/10/81 HM21A Casting Campaign, T. S. 

Johnson; Consolidated Aluminum Corporation - Madison Plant; September 10, 1981; SRDB Ref ID: 

40440 
SEC-00079 Addendum 2 06-03-08 Dow Madison

13 of 34 

USACE, 1999, Formerly Utilized Sites Remedial Action Program St. Louis Sites, Community 

Relations Plan, Revision 1, U.S. Army Corps of Engineers, January 1999; SRDB Ref ID: 43878 

USACE, 2000, Post-Remedial Action Report for the Madison FUSRAP Site, USACE Review Draft, 

U.S. Army Corps of Engineers, September 2000; SRDB Ref ID: 42409. 

USACE, 2001, Formerly Utilized Sites Remedial Action Program St. Louis Sites, Community 

Relations Plan, Revision 3, U.S. Army Corps of Engineers, January 2001; SRDB 40457 
SEC-00079 Addendum 2 06-03-08 Dow Madison

14 of 34 

This page intentionally left blank 
SEC-00079 Addendum 2 06-03-08 

15 of 34 

Attachment 1: Data Capture Matrices for Dow Chemical, Madison, Illinoi

Table A1-1: SUMMARY OF SRDB HOLDINGS RELATED TO DOW MADISON 

(This table spans two pages) 

Data Capture Information General Description of Documents Captured D

Primary Site/Company Name: Dow Chemical, Madison, IL 1947-1969  Other Site Names:  Spectrulite Consortium 1986-Present  CONALCO 1973-1986  CONALCO-Phelps Dodge Aluminum Corp. 1969-1973 

See DOW HQ, OCAS, NRC HQ, Stan A. Huber Consultants, Pangea Group, Illinois Emergency Management Agency below. 

State Contacted: Illinois Emergency Management Agency 

Licensing documents, decommissioning plans and surveys. 

DOE LM Considered Sites FUSRAP survey. NRC Agencywide Document Access and Management (ADAMS) 

FOIA requests and responses, licensing, and correspondence. 

Battelle Website No relevant data identified. Comprehensive Epidemiologic Data Resource (CEDR) No relevant data identified. DOE Hanford Declassified Document Retrieval System (DDRS) 

No relevant data identified. 

DOE OpenNet Metabolism & biological effects of Pu, Po, Ra, Th, U, and Pb-212. DOE Office of Scientific& Technical Information (OSTI) Energy Citations 

No relevant data identified. 

DOE Office of Scientific& Technical Information (OSTI) Information Bridge 

Rad safety considerations for thorium handling. 

Google Thorium information, FUSRAP documents, general information. National Academies Press (NAP) No relevant data identified. National Nuclear Security Administration (NNSA) - Nevada Site Office 

No relevant data identified. 

Washington State University (United States Transuranium and Uranium Registries) 

No relevant data identified. 

Claimant Information regarding former Dow president. 
SEC-00079 Addendum 2 06-03-08 

16 of 34 

Table A1-1: SUMMARY OF SRDB HOLDINGS RELATED TO DOW MADISON 

(This table spans two pages) 

Data Capture Information General Description of Documents Captured D

Dow HQ Rad safety assessments and bulletins, radiological survey results, 

Mg-Th alloy product specifications, annual IH summaries, licenses and licensing correspondence, affidavits, and purchase orders. 

DOE Germantown General facility information. Kansas City NARA DOE site remediation authority determination. NRC Public Reading Room Licensing correspondence and inspection reports including survey 

and air monitoring results. Review of CONALCO decommissioning plans, IH experience with Mg-Th alloys including welding, and license exemption request. 

Oak Ridge Site description and FOIA responses. Savannah River Site Trip report, FOIA requests and responses. OCAS Litigation summary, research paper on LEU fuel, SEC petition with 

affidavits, and request for certain records. 

OCAS Worker Outreach General information from the 08/2006 Worker Outreach Meeting. Kirkland & Ellis, LLP Letter describing Dow Chemical's records retention policies and 

search. 

Pangea Group Spectrulite air sample results summary from 2006 rafter 

decontamination. 

SAIC Radiation exposure summaries, 1960 and 1961. Stan A. Huber Consultants Low level rad waste manifest and sample analysis. First Gov Website Site activity summary. Wikipedia Thorium information. Unknown Site description and preliminary results of the 1990 radiological 

survey. 

TOTAL 
SEC-00079 Addendum 2 06-03-08 

17 of 34 

Table A1-2: INTERNET DATABASE SEARCHES RELATED TO DOW MADISON 

(This table spans four pages) 

DATABASE/SOURCE KEYWORDS / PHRASES 

DOE OSTI Information Bridge dow madison http://www.osti.gov/bridge/advancedsearch.jsp COMPLETED 01/09/2008 CONALCO 

CONALCO madison site Uranium Extrusion 

DOE OpenNet http://www.osti.gov/opennet/advancedsearch.jsp COMPLETED 01/09/2008 

DOW Chemical dow madison DOW Madison IL DOW Madison Site, Madison IL DOW Madison dow madison uranium extrusion 

NRC ADAMS Reading Room http://www.nrc.gov/reading-rm/adams/web-based.html COMPLETED 01/12/2008 

madison IL 

Wikipedia http://www.wikipedia.com COMPLETED 01/14/2008 

Hazards and Properties of Thorium Michigan Michigan Metallurgical Lab 

Battelle Website http://www.battelle.org COMPLETED 02/07/2008 

Metallurgical Lab madison uranium rod straightening Mallinckrodt Madison Mallinckrodt uranium straightening Mallinckrodt Dow Uranium Contract "dow chemical" "madison site" "uranium" spectrulite 

Google http://www.google.com COMPLETED 02/13/2008 

"madison site" extrusion 
SEC-00079 Addendum 2 06-03-08 

18 of 34 

Table A1-2: INTERNET DATABASE SEARCHES RELATED TO DOW MADISON 

(This table spans four pages) 

DATABASE/SOURCE KEYWORDS / PHRASES 

spectrulite uranium Uranium Extrusion madison site madison IL Mallinckrodt Madison Mallinckrodt uranium straightening Mallinckrodt DOW contract uranium Dow Madison Americium Dow Madison Thoron CONALCO Thoron Spectrulite Thoron Consolidated Aluminum Thoron Dow Madison Thorium Dow Madison Chemical 10-66 Dow Madison Chemical 10-12 Dow Madison Ionium Dow Madison myrnalloy Dow Madison UX1 Dow Madison UX2 Battelle Michigan Metallurgical Laboratory Battelle Metallurgical Battelle Metallurgical Michigan Battelle Michigan Dow Madison Th230 Dow Madison Th 230 Dow Madison Th 230 or Th-230 or Th230 Dow Madison Th-230 Spectrulite th 230 
SEC-00079 Addendum 2 06-03-08 

19 of 34 

Table A1-2: INTERNET DATABASE SEARCHES RELATED TO DOW MADISON 

(This table spans four pages) 

DATABASE/SOURCE KEYWORDS / PHRASES 

Spectrulite th-230 Th-232 Magnesium Casting Dross Spectrulite Th230 Spectrulite th-230 US Federal Court Michigan Eastern District "dow chemical" "madison site" dow uranium rod straightening CONALCO "Consolidated Aluminum" madison site uranium extrusion process DOW Chemical Madison Site Thorium Magnesium Dosimetry "Thorium Magnesium" and Dosimetry "Thorium Magnesium" and Properties Thorium alloys "Magnesium Thorium" and hazards "Thorium Production Technology" "Health and Safety Aspects of Thorium Production" "Health Hazards Associated with Rolling Normal and Enriched Uranium" Industrial Hygiene and Medical Survey of a Thorium Refinery "Thorium Hazards" in Title "Thorium Dosimetry" in Title Thorium Handling in Title Thorium Magnesium in Title "Thorium Hazards" in Title 
SEC-00079 Addendum 2 06-03-08 

20 of 34 

Table A1-2: INTERNET DATABASE SEARCHES RELATED TO DOW MADISON 

(This table spans four pages) 

DATABASE/SOURCE KEYWORDS / PHRASES 

"Thorium Dosimetry" in Title Thorium Handling in Title Thorium Magnesium in Title Thorium Metabolism "Thorium Hazards" in Title "Thorium Dosimetry" in Title Thorium Handling in Title Thorium Magnesium in Title 

Hanford DDRS DOW Madison http://www2.hanford.gov/declass/ COMPLETED 04/08/2008 Madison National Academies Press DOW Madison http://www.nap.edu/ COMPLETED 04/08/2008 Madison NNSA - Nevada Site Office DOW Madison www.nv.doe.gov/main/search.htm COMPLETED 04/08/2008 Madison 

DOE CEDR http://cedr.lbl.gov/ COMPLETED 04/08/2008 

CEDR http://cedr.lbl.gov 

U.S. Transuranium & Uranium Registries DOW Madison http://www.ustur.wsu.edu/ COMPLETED 04/08/2008 

Madison 

Energy Citations Database "Dow Madison" http://www.osti.gov/energycitations/ COMPLETED 04/10/2008 

Dow Madison 
SEC-00079 Addendum 2 06-03-08 

21 of 34 

Table A1-3: OSTI DOCUMENTS REQUESTED FOR DOW MADISON 

DOCUMENT NUMBER DOCUMENT TITLE 

None Requested 
SEC-00079 Addendum 2 06-03-08 Dow Madison

22 of 34 

This page intentionally left blank 
SEC-00079 Addendum 2 06-03-08 Dow Madison

23 of 34 

Attachment 2: Reconstruction of Dose Resulting from Intake of 

Residual Thorium at Dow Chemical from 1961 through 2006 

1.0 Introduction 

Dow Madison supplied the Atomic Energy Commission (AEC) with both materials and services from 

January 1, 1957 through December 31, 1960. Among these materials and services, Dow Madison 

provided magnesium-thorium (Mg-Th) sheets and plates to Mallinckrodt and other AEC facilities. The 

DOE has stated that in 1957 and 1958 Dow Madison supplied the AEC (via the Mallinckrodt site) with 

Mg-Th plates and sheets, and that during the 1957 and 1958 time period, these types of plates and 

sheets were used in atomic weapons (DOE, 2008). The DOE concluded that, for the years 1957-58: 

(1) Dow Madison probably produced material for use by the AEC; (2) the material emitted radiation; 

(3) the material could have been used in the production of an atomic weapon; and (4) Dow Madison’s 

work with Mg-Th plates and sheets is, therefore, a covered AWE operation (DOE, 2008). The Dow 

Madison AWE operations period (1957 through 1960) has already been designated part of the Special 

Exposure Cohort. The SEC evaluation determined that doses received from potential exposure to 

uranium contamination during the residual period (1961 through 2006) can be bounded; this bounding 

methodology is presented in the Dow Madison SEC Evaluation Report (NIOSH, 2007). This analysis 

only considers the bounding of doses received from potential exposure to thorium during the residual 

period. Thorium operations are discussed in Section 4.1 of Addendum 2. An understanding of 

thorium operations and the pertinent data during the AWE operations period (discussed below) is 

required in order to establish the foundation and assumptions for bounding thorium doses during the 

residual period. 

2.0 Data Considered 

Empirical data and process descriptions of arc-melting of thorium metals are provided in a formal 

study (Lowery, 1962). Arc-melting was used at Dow Madison. While the Lowery data are not used 

directly in determining intake in the bounding analysis, the study is important to demonstrate expected 

air concentrations of thorium and thorium progeny. The study also measured airborne activity 

(breathing zone and general area) in the major task areas involved with arc-melting thorium. Air 

sampling data obtained at Dow Chemical, Midland for Mg-Th operations are provided in a Health 

Physics Society presentation document (Silverstein, 1957). 

NIOSH analyzed the available data and bounded the airborne activity during the residual period using 

the highest general area air sample collected from 1957 through 1959 (Hoyle, 1957; Dow, 1959; 

Shrader, 1959). Process and breathing zone samples were excluded, the rationale being that general 

area air samples collected during operations would adequately represent contributions from both resuspension of surface contamination and dispersion of process releases and, as such, would bound the 

contribution from re-suspension of surface activity alone during the residual contamination period. In 

all, NIOSH has thirteen general area results for the years 1957 through 1960. 
SEC-00079 Addendum 2 06-03-08 Dow Madison

24 of 34 

These air monitoring data are presented in Table 2-1. Only two of the thirteen results were positive. 

All results were converted to pCi/m3

 by using the specific activity of thorium-232. For values reported 

as < n (e.g., < 0.001), the numeric value was used as the absolute value (e.g., < 0.001 = 0.001) and 

converted to pCi/m3

. 

Table 2-1: Thorium Air Monitoring Data 

Task, Area or Process Time 

Frame 

SRDB 

Ref ID 

Sample 

ID 

Reported 

Thorium 

(mg/m3) 

Calculated 

Conc. 

(pCi/m3) 

R. M. Salvage (range of results) Dec-57 39912, 

pdf pg 7 

 0.018 2.00 

R. M. Salvage (range of results) Dec-57 39912, 

pdf pg 7 

 0.036 4.00 

Rolling steam annealed HK31 in #2 Mill 

(range of results) 

Mar-59 39912, 

pdf pg 7 

 <0.009 1.00 

Rolling steam annealed HK31 in #2 Mill 

(range of results) 

Mar-59 39912, 

pdf pg 7 

 <0.015 1.70 

Centrifuge - HK31 sludge Dec-59 39914, 

pdf pg 7 

10 <0.010 1.11 

Centrifuge - HK31 sludge Dec-59 39914, 

pdf pg 7 

12 <0.011 1.22 

Near instrument panel Dec-59 39914, 

pdf pg 7 

9 <0.011 1.22 

Next to drums in sludge recovery Dec-59 39914, 

pdf pg 7 

14 <0.011 1.22 

Sludge recovery Dec-59 39914, 

pdf pg 7 

6 <0.011 1.22 

Sludge recovery Dec-59 39914, 

pdf pg 7 

8 <0.011 1.22 

Control panel Dec-59 39914, 

pdf pg 7 

11 <0.013 1.44 

Near control panel Dec-59 39914, 

pdf pg 7 

2 <0.023 2.56 

Near control panel Dec-59 39914, 

pdf pg 7 

4 <0.076 8.44 
SEC-00079 Addendum 2 06-03-08 Dow Madison

25 of 34 

Oak Ridge National Laboratory (ORNL) performed a radiological survey at the Dow Madison site in 

March 1989 and published a survey report in December 1990 (ORNL, 1990). Among the data 

published in the report are results from surface smears and dust samples taken in Building 6 where 

uranium extrusion and thorium processing were performed. ERG collected soil samples and air 

monitoring data prior to, and after, the 1992 waste yard remediation (Huber, 1998; Baker, 1992). 

Pangea performed worker and area air monitoring during thorium clean-up operations conducted in 

2006. Pangea Group monitored workers for a four-month period (June through October) for exposure 

to airborne thorium. Air monitoring results were provided for workers wearing respiratory protection, 

for workers working using no respiratory protection, and for the perimeter stations. Workers involved 

in vacuuming and direct removal of dust wore respirators. A Pangea memo states that after Pangea 

collected information on the workers involved in clean-up activities for one month, it was decided that 

because airborne activity levels were below 10% of the Derived Air Concentration (DAC) values, 

workers would no longer be required to use respiratory protection for vacuuming activities (Cushman, 

2008). The highest air concentrations measured for workers wearing no respiratory protection, and at 

the perimeter stations, would have represented airborne conditions that would have been present in the 

latter year of the residual period during operations that resulted in re-suspension of thorium dust. The 

maximum air concentrations observed were 9.94% of DAC based on Class Y thorium-232 at the 

perimeter, and 9.67% of DAC for workers not wearing respiratory protection. The corresponding 

DAC for Class Y thorium-232 is 1.0 pCi/m3

. 

3.0 Exposures to Residual Thorium 

Internal exposures to thorium during the residual period potentially resulted from corrosion of stored 

material, re-suspension of dust, scrap handling, scrap cutting, and loss of containment of disposed 

materials. Internal exposures to thorium can be bounded based on the available information on the 

Dow Madison alloy process, the ventilation, the protections employed, and the decay/equilibrium 

assumptions provided in the Silverstein presentation (Silverstein, 1957). 

A statistical analysis of the thirteen data points presented in Table 2-1 would provide uncertain results 

since only two of the results were reported as positive. The greatest positive result was 4 pCi/m3. 

However, the greatest result when all data are considered is 8.44 pCi/m3

. This value was used to 

maximize the concentration in air of Th-232 during AWE operations with Mg-Th alloy. 

Given the available process knowledge reported by Dow Chemical and available air monitoring 

results, NIOSH considers the maximum air concentration (8.44 pCi/m3

 of Th-232) derived from the 

data in Table 2-1 to adequately bound the air concentration for potential internal exposures to residual 

AWE thorium at the start of the residual radiation period (beginning on January 1, 1961). 
SEC-00079 Addendum 2 06-03-08 Dow Madison

26 of 34 

Contemporary estimates of airborne radioactivity can be derived by using the 1961 air concentration 

and the air monitoring data obtained in 2006 (Cushman, 2008). Based on removal mechanisms 

described in ORAUT-OTIB-0070, an exponential model was used to fit the 1961 air concentration and 

the 2006 data: 

A(residual period) = A(operations) * e -λt with t being the length of time between the two air 

concentration measurements (2006 and 1961, respectfully). This equation was then solved for 

the factor λ. 

The maximum derived air concentration for non-protected operations measured at Dow Madison in 

2006 was 0.0994 pCi/m3

 (9.94% DAC). Using the equation above yields 

λ = 0.0987 year -1

Using the factor λ, calculated above, air concentrations may be calculated for each year (the air 

concentration is assumed to be steady for the entire year) and annual inhalation intakes may be 

calculated by multiplying the concentration value times 1.2 m3/hr and 2000 hours/yr. For 2006, the 

annual intake was calculated to be 239 pCi. Annual inhalation intakes of Th-232 for all years are 

shown in Table 3-2. 

Table 3-2: Annual inhalation intakes 

Year Thorium-232 

(pCi/yr) 

Year Thorium-232 

(pCi/yr) 

1/1/1961 20256 1/1/1984 2092 

1/1/1962 18352 1/1/1985 1896 

1/1/1963 16627 1/1/1986 1718 

1/1/1964 15065 1/1/1987 1556 

1/1/1965 13649 1/1/1988 1410 

1/1/1966 12366 1/1/1989 1277 

1/1/1967 11204 1/1/1990 1157 

1/1/1968 10151 1/1/1991 1049 

1/1/1969 9197 1/1/1992 950 

1/1/1970 8332 1/1/1993 861 

1/1/1971 7549 1/1/1994 780 

1/1/1972 6840 1/1/1995 707 

1/1/1973 6197 1/1/1996 640 

1/1/1974 5614 1/1/1997 580 

1/1/1975 5087 1/1/1998 525 

1/1/1976 4609 1/1/1999 476 

1/1/1977 4176 1/1/2000 431 

1/1/1978 3783 1/1/2001 391 

1/1/1979 3428 1/1/2002 354 

1/1/1980 3105 1/1/2003 321 

1/1/1981 2814 1/1/2004 291 

1/1/1982 2549 1/1/2005 263 

1/1/1983 2310 1/1/2006 239 
SEC-00079 Addendum 2 06-03-08 Dow Madison

27 of 34 

Internal doses from ingestion can then be bounded using the annual inhalation intake rates. Per 

OCAS-TIB-009, the intake can be clamant-favorably reconstructed by assuming the total daily ingestion 

intake equals 0.2 times the air concentration (NIOSH, 2004). The annual ingestion intake is then 

calculated based on 250 workdays per year. The same clearance factor that is used with inhalation dose 

determinations should be used with accompanying ingestion dose determinations. Annual ingestion 

intakes of Th-232 are shown in Table 3-3. 

Table 3-3: Annual ingestion intakes 

Year Thorium-232 

(pCi/yr) 

Year Thorium-232 

(pCi/yr) 

1/1/1961 422.0 1/1/1984 44.1 

1/1/1962 382.3 1/1/1985 40.0 

1/1/1963 346.4 1/1/1986 36.3 

1/1/1964 313.9 1/1/1987 32.9 

1/1/1965 284.4 1/1/1988 29.9 

1/1/1966 257.7 1/1/1989 27.2 

1/1/1967 233.5 1/1/1990 24.7 

1/1/1968 211.6 1/1/1991 22.4 

1/1/1969 191.7 1/1/1992 20.4 

1/1/1970 173.8 1/1/1993 18.6 

1/1/1971 157.5 1/1/1994 16.9 

1/1/1972 142.7 1/1/1995 15.4 

1/1/1973 129.3 1/1/1996 14.0 

1/1/1974 117.2 1/1/1997 12.8 

1/1/1975 106.2 1/1/1998 11.7 

1/1/1976 96.3 1/1/1999 9.9 

1/1/1977 87.3 1/1/2000 9.0 

1/1/1978 79.1 1/1/2001 8.1 

1/1/1979 71.8 1/1/2002 7.4 

1/1/1980 65.1 1/1/2003 6.7 

1/1/1981 59.0 1/1/2004 6.1 

1/1/1982 53.5 1/1/2005 5.5 

1/1/1983 48.6 1/1/2006 5.0 

3.1 Exposures to Thorium Slag 

Intakes must also be considered from potential exposures arising from the waste yard through the end 

of 1992 when remediation was completed (Baker, 1992). Workers involved in waste yard activities 

would have been potentially exposed to these intakes, but not to both the building and waste yard 

intakes at the same time. 
SEC-00079 Addendum 2 06-03-08 Dow Madison

28 of 34 

There were 130,000 pounds (59,000 kg) of thorium in the yard, as reported in 1986 (Mura, 1986). It is 

assumed that Dow Chemical put solid slag waste in this yard from 1957 through 1969. While waste 

was absorbed in soil, it is possible that some soil and waste material was blown airborne or spread via 

equipment and workers after dumping/bulldozing operations. Although materials in the waste yard 

were covered, some breach of covering is assumed to be plausible. As a bounding estimate, it is 

assumed that the entire AWE waste inventory was available for release to the environment, and that it 

was released in equal annual quantities (1844 kg) from 1961 through 1992 using a release fraction of 

0.001. Using the specific activity of Th-232, there are 0.208 curies of radioactivity in 1844 kg. 

The annual inhalation intake (I) can be calculated using: 

1. I = 10-6 * Q * R * C * D (NUREG-1400), 

where: 

Q = annual activity of radionuclide = 0.208 Ci 

R = estimated release fraction = 0.001 

 (NUREG-1400 recommends R = 0.001 for solids) 

C = confinement factor = 1 

 (NUREG-1400 recommends C = 1 for open areas) 

D = dispersibility factor = 1 

 (No dispersion energy is assumed to be added to the waste after disposal in the yard) 

2. From this equation, I is determined to be: 

I = 10-6 * 0.208 * 0.001 * 1 * 1 

I = 2.08E-10 Ci per year 

I = 208 pCi per year (inhalation) 

Since the intake calculated for yard workers (208 pCi/yr) is bounded by that calculated in Section 3.0, 

above, the higher intake rates provided in Table 3-2 (for inhalation) and Table 3-3 (for ingestion) 

should be assumed for all workers. 
SEC-00079 Addendum 2 06-03-08 Dow Madison

29 of 34 

3.2 Exposure to Thoron 

Thoron (Rn-220) and its progeny are part of the thorium decay series and thoron air contamination 

would have been present during the operations period. Dow Madison monitored for thoron 

contamination in 1959 during operations that used HK-31 (the alloy containing the highest percentage 

of thorium). These monitoring data (Shrader, 1959) are shown in Table 3-4. 

Table 3-4: Thoron Air Monitoring Data 

Task, Area or Process Sample 

Date 

SRDB Ref ID Sample 

ID 

Thoron and 

Progeny (Ci/l) 

In Pot Room Dec-59 39914, pdf p. 7 3 2.0E-12 

Near control panel Dec-59 39914, pdf p. 7 4 1.0E-13 

Sludge recovery Dec-59 39914, pdf p. 7 6 3.7E-14 

Near instrument panel Dec-59 39914, pdf p. 7 9 3.4E-14 

Centrifuge - HK31 sludge Dec-59 39914, pdf p. 7 10 3.2E-14 

Near control panel Dec-59 39914, pdf p. 7 2 3.1E-14 

Next to drums in sludge recovery Dec-59 39914, pdf p. 7 14 2.3E-14 

Centrifuge - HK31 sludge Dec-59 39914, pdf p. 7 12 2.0E-14 

In Pot Room Dec-59 39914, pdf p. 7 7 2.0E-14 

Control panel Dec-59 39914, pdf p. 7 11 1.6E-14 

In Pot Room Dec-59 39914, pdf p. 7 1 1.3E-14 

In Pot Room Dec-59 39914, pdf p. 7 5 1.2E-14 

Sludge recovery Dec-59 39914, pdf p. 7 8 5.0E-15 
SEC-00079 Addendum 2 06-03-08 Dow Madison

30 of 34 

A z-score analysis was applied to these data, as shown in Table 3-5. The z-score for an item indicates 

how far, and in what direction, that item deviates from the mean of its distribution, expressed in units 

of that distribution's standard deviation. The resulting Rn-220 concentration at the 95th percentile was 

1.82E-13 Ci/l (0.182 pCi/l). 

Table 3-5: Z-Score Analysis of Thoron Air Monitoring Data 

Rank Thoron 

(Ci/l) 

Ln 

(Data) 

Percentile Z-Score 

1 5.00E-15 -32.93 0.04 -1.77 

2 1.20E-14 -32.05 0.12 -1.20 

3 1.30E-14 -31.97 0.19 -0.87 

4 1.60E-14 -31.77 0.27 -0.62 

5 2.00E-14 -31.54 0.35 -0.40 

6 2.00E-14 -31.54 0.42 -0.19 

7 2.30E-14 -31.40 0.50 0.00 

8 3.10E-14 -31.10 0.58 0.19 

9 3.20E-14 -31.07 0.65 0.40 

10 3.40E-14 -31.01 0.73 0.62 

11 3.70E-14 -30.93 0.81 0.87 

12 1.00E-13 -29.93 0.88 1.20 

13 2.00E-12 -26.94 0.96 1.77 

RESULTS:

GM (50th): 3.14E-14 Ci/l 

GM*GSD (84th): 1.10E-13 Ci/l 

GSD: 3.505 

95th Percentile: 1.82E-13 Ci/l 

r squared: 0.719 

3.3 Summary of Internal Intakes 

Intake values for inhalation and ingestion should be assigned for each year of employment. Equal 

intake amounts should be attributed to Th-232, Th-228, and Ra-228. An intake of Th-230 should be 

added based on a 2:1 activity ratio of Th-230 to Th-232 (Baker, 1992). Thoron intake should also be 

assigned for each year of employment. These intakes must be added to intakes arising from potential 

exposures to residual uranium, as discussed in the Evaluation Report for Dow Madison Petition 

SEC-00079 (NIOSH, 2007). 
SEC-00079 Addendum 2 06-03-08 Dow Madison

31 of 34 

3.4 External Exposures 

External electron and photon exposures resulting from exposure to thorium feed can be reconstructed 

using dose rate data presented by Silverstein and by Levy (Silverstein, 1957; Levy, 1957). Exposure 

rate data obtained in 1982 are useful in reconstructing potential external doses. External radiation 

measurements were obtained for CONALCO during commercial thorium processing and during 

non-processing periods and represent exposure rates generated from materials of varying in-growth. 

CONALCO concluded in the document that all external radiation levels were maintained within 

allowable limits. Exposure rates measured in all areas, except near the thorium scrap bins and storage 

annex, ranged from 0.01 to 0.05 mR/hr at distances varying between one and ten feet. The highest 

recorded exposure rate (0.7 mr/hr at one foot) was obtained near the thorium storage area and scrap 

bins, where AWE era materials were stored. The exposure rate recorded at ten feet ranged from 0.1 to 

0.2 mr/hr. 

While thorium scrap and wastes generated during the AWE operations period would have only 

partially contributed to the measured photon exposure rates, the measured exposure data are assumed 

to represent the doses from those AWE materials with no scaling factor applied. These data can be 

used to bound the external photon dose by assuming that all workers were continuously exposed to the 

maximum recorded exposure rate (0.7 mr/hour) during a 40-hour week. In this scenario, a worker 

would have received 28 mrem/week whole-body photon exposure per week or 1.400 rem/year. In 

considering the electron exposure rate, Heatherton reported that beta dose rates due to thorium metal 

with in-growth of daughters were approximately in a 1:1 ratio with the photon dose rate (Heatherton, 

1955). Therefore, an annual beta dose of 1.400 rem/year will be used for the electron dose for all 

workers. The photon and electron doses are additive to the photon and skin dose assigned from 

potential exposures from residual uranium (ORAUT- OTIB-0004; Eckerman, 1993). 
SEC-00079 Addendum 2 06-03-08 Dow Madison

32 of 34 

This page intentionally left blank 
SEC-00079 Addendum 2 06-03-08 Dow Madison

33 of 34 

4.0 References 

OCAS-TIB-009, Estimation of Ingestion Intakes, Rev. 0, Office of Compensation Analysis and 

Support (OCAS); National Institute for Occupational Safety and Health (NIOSH); April 13, 2004; 

SRDB Ref ID: 22397 

ORAUT-OTIB-0004, Estimating the Maximum Plausible Dose to Workers at Atomic Weapons 

Employer Facilities, Rev 03 PC-2; Oak Ridge Associated Universities (ORAU); Oak Ridge, 

Tennessee; December 6, 2006; SRDB Ref ID: 29949 

ORAUT-OTIB-0070, Dose Reconstruction During Residual Radioactivity Periods at Atomic Weapons 

Employer Facilities, Rev 00; ORAU Team Dose Reconstruction Project for NIOSH; March 10, 2008; 

SRDB Ref ID: 41603 

Baker, 1992, Madison Site Cleanup, Final Report, prepared by Ken Baker, Environmental Restoration 

Group, December, 1992; SRDB Ref ID: 43582 

Cushman, 2008, Email concerning Madison Site, Matt Cushman, Pangea Group; March 5, 2008; 

SRDB Ref ID: 41940. 

DOE, 2008, Letter from Department of Energy to Department of Labor, January 8, 2008; SECIS 

SRDB Document ID: 105199 

Dow, 1959, Annual Industrial Hygiene Summary May 1959, D. J. Levy and H. R. Hoyle; Dow 

Chemical Corporation, July 27, 1959; SRDB Ref ID: 39912 

Eckerman, 1993, External Exposure to Radionuclides in Air, Water, and Soil, Federal Guidance Report 

No. 12; Environmental Protection Agency and Oak Ridge National Laboratory; September, 1993; 

SRDB Ref ID: 11997 

Heatherton, 1955, Radiation from Thorium Materials, National Lead of Ohio, April, 19, SRDB Ref ID: 

42354. 

Hoyle, 1957, Thorium Handling, Alpha Counters and Sludge Recovery Hazards, H. R. Hoyle; Dow 

Chemical Corporation; December 20, 1957; SRDB Ref ID: 39998 

Huber, 1998, Uniform low-level radioactive waste manifests and other documents, Stan A. Huber and 

Associates, 1998; SRDB Ref ID: 41934 

Levy, 1957, Memo from D. J. Levy, Dow Chemical Company, Madison, IL, March 8, 1957; SRDB 

Ref ID: 39977 

Lowery 1962, Radiation Hazards in Arc Melting Thorium, Report of Investigations 5969, R. R. 

Lowery, Department of the Interior, 1962; SRDB Ref ID: 40074 

Mura, 1986, Memo and attachments from William Mura (CONALCO) to Bruce Mallet (NRC), 

Consolidated Aluminum Company; August 21, 1986; SRDB Ref ID: 29727, pdf pp. 4-5 
SEC-00079 Addendum 2 06-03-08 Dow Madison

34 of 34 

NIOSH, 2007, SEC Petition Evaluation Report Petition SEC-00079, National Institute for 

Occupational Safety and Health, November 28, 2006; SRDB Ref ID: 39873. 

NUREG-1400, Air Sampling in the Workplace, Final Report, Nuclear Regulatory Commission, 

September, 1993; SRDB Ref ID: 20129 

ORNL, 1990, Preliminary Results of the Radiological Survey at the Former Dow Chemical Company 

Site, Madison, Illinois; ORNL/TM-11552, W. D. Cottrell and J. K. Williams; December, 1990; SRDB 

Ref ID: 3947 

Shrader, 1959, Air Sample Data and Calculations, S. A. Shrader; Dow Chemical Corporation; 

December 16, 1959; SRDB Ref ID 39914 

Silverstein, 1957, Industrial Hygiene Experience with Magnesium-Thorium Alloys, Lawrence G. 

Silverstein, Dow Chemical Corporation, June 19, 1957; SRDB Ref ID: 29269.